Doctor blade and doctor blade shear for textile printing machine



March 14, 1961 F. w. HUNT 2,974,586

DOCTOR BLADE AND DOCTOR BLADE SHEAR FOR TEXTILE PRINTING MACHINE Filed April 19, 1960 INVENTOR Foresf W. Hunt HKMMA.

ATTORNEY United States Patent DOCTOR BLADE AND DOCTOR BLADE SHEAR FOR TEXTILE PRINTING MACHINE The present invention relates broadly to improvements in textile printing, and more particularly to an improved doctor blade shear or mounting for the doctor blade used in conjunction with the engraved roll of a textile printing machine.

In the printing of textile fabrics, a copper roll which i is engraved with the design to be printed rotates against a press cylinder and prints the design upon cloth passing over the press cylinder. The color paste is supplied to the'engraved roll by a furnisher roll that rotates against the engraved copper roll. The furnisher roll rotates in a font containing the printing paste and, as it contacts the engraved roll, deposits the color therein. The engraved roll, however, when it rotates against the cloth to be printed, should have this color paste only in the depressions of the engraving, but the furnisher roll deposits color not only in the engraving but also wherever it contacts the engraved roll, both within and without the engraved design throughout its length. Accordingly, a sharp doctor blade is provided to clean the engraved roll, that is, to scrape olf all the paste deposited thereon except where it is contained in the intaglio design.

This doctor blade is usually a razor sharp steel blade which is kept pressed against the engraved roll and which scrapes the excess paste therefrom so that it flows back into the font. The doctor blade has its edge beveled upon one side, and the beveled side of the edge faces away from the periphery of the engraved roll.

In the prior art, the above-mentioned doctor blade has always been formed straight or flat and the doctor blade is rigidly secured by bolting to a holder or shear which is also straight or flat. The shear may be formed of metal or wood or any other suitable material.

In' printing where there is no slash, this straight doctor blade is very effective. However, it is necessary to slash much textile printing work, that is to say, the doctor blade must operate against a pattern on the engraved roll, which pattern is set at an angle. The present accepted method of doing this is to place the engraved pattern on the engraved roll on the bias or in a spiral around the periphery of the roll rather than normal to the axis of the engraved roll. This necessitates the use of slash bars so that the cloth itself is pulled at an angle or on the bias around the press cylinder. This slashing of the cloth is done largely by guesswork and results in uneven color and shaded fabric since the slashing is not perfect.

The object of this invention is to permit the doctor blade itself to be slashed at an angle to the longitudinal axis of the engraved roll in such a manner that it engages the engraved roll at a uniform pitch throughout the entire length of the engraved roll and the beveled edge of the doctor blade conforms accurately to the shape of the engraved roll throughout the length of the doctor blade and such roll.

According to the present invention, the holder or shear ice of the same which is uniform and calculated so as to present the beveled edge of the doctor blade to the periphery of the engraved roll uniformly or at a constant pitch along the length of the latter. The beveled edge of the doctor blade is slashed or set at an angle to the engraved roll and actually engages the periphery of the roll along a spiral line or path, and the incidence'of the edge of the doctor blade against the engraved roll is perfectly uniform and uniformly effective for scraping the engraved roll along the entire line of contact between the doctor blade and roll.

This is not possible with the use of a straight or flat doctor blade and doctor blade shear as employed in the prior art. With the latter, when the doctor blade is slashed at an angle to the engraved roll, one portion of the doctor blade lies relatively fiat or tangent against the periphery of the roll and the other end portion of the doctor blade presents a sharp edge against the engraved roll and has a heavy dragging or scraping effect upon the roll. Intermediate these end portions of the doctor; blade, the condition of incidence varies between flat engagement and edgewise engagement 'with the roll, which is undesirable. The result is that the engraved roll applies more color to the cloth on one end than near the other end. This results in color shaded fabric and also causes worn or dipped engraving on the engraved roll. All of these difficulties are entirely overcome and eliminated by the use of the improved doctor blade and doctor blade shear according to the invention. In the present invention, when the doctor blade is 'slashed to the engraved roll, its beveled edge engages the periphery of the roll evenly and this results in a perfectly uniform scraping of the entire engraved roll, resulting in even removal of excess coloring material, perfectly uniform fabric printing and low and even wear on the engraved roll.

Other objects and advantages of the invention will become apparent during the course of the following description.

In the accompanying drawings forming a part of this application and in which like numerals are employed to designate like parts throughout the same,

Figure 1 is a fragmentary side elevation of textile printing apparatus having the invention applied thereto.

Figure 2 is a vertical section taken on line 22 of Figure 1.

Figure 3 is a side elevation of a doctor blade and doctor blade shear according to the invention, separated from the printing apparatus.

Figures 4, 5 and 6 are transverse vertical sections taken on lines 44, 5-5 and 6-6 of Figure 3.

In the drawings, wherein for the purpose of illustration is shown a preferred embodiment of the invention, the numeral 10 designates a press cylinder which may be suitably blanketed and about which the cloth 11 to be printed is drawn in the usual manner. The cloth 11 passes between the press cylinder 10 and an engraved roll 12 as shown in Figure 2 and the cylinder 10 and roll 12 are suitably journaled upon the frame 13 of the printing apparatus.

A furnisher roll 14 mounted below the engraved roll 12 and contacting the latter rotates in a font 15 containing the color paste. The furnisher roll rotates in a reverse direction to the engraved roll and applies the coloring material thereto in the usual manner. apparatus shown is generally the same as the printing apparatus disclosed in prior United States Patent 2,404,689, to Carlsen et al.

The improved doctor blade and doctor blade shear according to the present invention is shown generally at 16, and comprises a two-part shear or holder 17 including companion elongated bars 18 and 19, formed of metal, wood or any other preferred material having the The '5 a necessary strength characteristics. The shear sections 18 and 19 are arranged in opposed relation throughout their lengths and are formed with a spiral or twist confiiguration longitudinally and in a uniform manner. The inner opposed faces 20 of the shear sections thus constitute in assembly a continuous spiral shaped slot 21, which receives an originally flat elongated doctor blade 22, preferably formed of steel or the like and having its leading or working edge beveled on one side, as at 23, to provide a very sharp edge thereon.

The slot 21 for the doctor blade is in effect a twisted or spiral slot axially of the longitudinal axis of the shear 17, as clearly shown in Figure 3 and in the cross sections, Figures 4 through 6. The doctor blade 22 is clamped in the spirally twisted position shown in Figure 3 by a plurality of longitudinally spaced bolts 24, engaging through openings in the shear sections 18 and 19 and the doctor blade, as shown in Figures 4 through 6. The assembly thus formed is rigid and the doctor blade will remain in the spiral or twisted shape.

Stub shafts 25 are suitably rigidly anchored within the ends of the shear 17, as at 26, and these shafts are held in suitable support elements 27, fixedly mounted upon the sides of the printing machine frame 13.

During use, the sharpened edge of the doctor blade directly engages the periphery of the engraved roll 12, as indicated in Figure 2, and the beveled side 23 of the sharpened edge faces away from the roll 12. The doctor blade 22 is mounted at an angle to the periphery of the roll 12, Figure 2, but the sharpened edge of the doctor blade contacts the periphery of the roll 12 evenly and in a uniform manner throughout the entire length of the doctor blade and roll, as previously explained, and so as to provide the advantages enumerated. The arrange ment is such that there is no tendency for one end portion of the doctor blade 22 to lie fiat or tangent to the periphery of the roll 12 while the other end portion scrapes the engraved roll harshly, and all portions of the sharpened edge of the doctor blade have a uniform pitch with respect to the engraved roll due to the spiral twist imparted to the doctor blade by the spirally twisted shear 17 The sharpened edge of the doctor blade is urged constantly against the engraved roll either manually or by any conventional means such as the spring means indicated at 28 in Figure 1.

Figures 4, 5 and 6 illustrate the angular disposition of the doctor blade 22 relative to the vertical at various points along the assembly as illustrated in Figure 3.

As the printing apparatus operates to print the cloth, the doctor blade removes from the roll 12 the excess coloring material with perfect uniformity and the excess material flows back into the font 15. The wear on the roll 12 is minimized and made uniform due to the twisted configuration of the doctor blade 22 and the uniform contact of the doctor blade edge against the engraved roll. The printing of the cloth 11 is also uniform and even, due primarily to the use of the improved doctor blade.

It is to be understood that the form of the invention herewith shown and described is to be taken as a preferred example of the same, and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of the invention or the scope of the subjoined claims.

Having thus described my invention, 1 claim:

1. A doctor blade assembly for use upon a fabric printing apparatus comprising a companion pair of doctor blade shear sections disposed in opposed relation and being spirally twisted longitudinally to provide spirally twisted meeting faces upon the shear sections, a doctor blade disposed between said spirally twisted faces and being spirally twisted and conforming to the shape of said faces and having a beveled edge to engage the pcriphery of the engraved roll of the printing apparatus, means to clampingly secure the shear sections and doctor blade together in assembly, and trunnion means carried by opposite ends of said assembly to facilitate mounting the assembly upon the printing apparatus.

2. In a fabric printing machine, an engraved roll, a press cylinder engaging the engraved roll whereby the fabric to be printed may be drawn between the engraved roll and press cylinder, a furnisher roll to supply coloring material to the engraved roll, a font containing the coloring material and receiving the furnisher roll, a doctor blade shear arranged near one side of the engraved roll and set at an angle to the axis of the engraved roll and being spirally twisted, and a doctor blade secured to said shear and being spirally twisted and conforming to the twisted shape of the shear and having a beveled edge engaging the periphery of the engraved roll at a uniform pitch along the entire length of the doctor blade and adapted to remove excess-coloring material from the engraved roll uniformly.

3. A doctor blade assembly for use on fabric printing apparatus in conjunction with the engraved roll of such apparatus and comprising an elongated spirally twisted doctor blade shear, and an elongated initially fiat doctor blade secured to said shear and receiving the twist of the shear and retaining such twist while secured to the shear and having an edge engageable with the engraved roll in a uniform manner along the entire line of contact between said edge and the periphery of the engraved roll.

4. In a fabric printing machine, an engraved roll to supply coloring material to the fabric, and a spirally twisted elongated doctor blade mounted adjacent the engraved roll and having a spirally twisted sharp edge to engage the periphery of the engraved roll with uniform 5 incidence along the entire length of the doctor blade.

No references cited. 

